In collaboration with Macquarie and Peking universities IPAS
researchers have found a way to make upconverting nano crystals 70%
brighter, paving the way for improvements in applications from
biosensing to security inks and with potential to remove barriers which
currently limit the sensitivity of sensors.
Upconverting nanocrystals are really useful but until now their
brightness has been seriously limited by internal quenching that occurs
at rather low concentrations of activator ions within the crystals. The
authors found that by hitting the nanocrystals with a much more powerful
beam of light the concentration of those activator ions in the
nanocrystals can be increased up to sixteen times before the brightness
of the upconverted emission began to tail off. These nanocrystals were
so bright that the ability to track a single crystal as in solution as
it was drawn into a dip sensor made from a Microstructured Optical Fibre
was reported in the paper “Single-nanocrystal sensitivity achieved by enhanced upconversion luminescence“.